In this tab we can pre-define Templates to pre-define Artificial Tasks. We have to simply put a Template's 'Name', 'Description' and individual Task names on the 'Task List' followed by pressing the 'Save' button. This will result in the group of tasks being arranged in an independent micro-structure, which later on can be re-used as a template in our Gantt.
In order to achieve a pre-configured arrangement of that sort, we need to use the relative dates column. Relative, because the numbers you put there are counted since the Parent Task (if there is any). Once saved, the template will appear in our Task Templates list in the '+Task' menu and we will be free to fit in our structure in any desired with pre-defined dependency rules.
This is very handy feature when we manage a complex projects with reusable sets of tasks. For example, once we have some 'Marketing' stories in our project along with 'Development' stories which we re-use every Sprint or so, we can create specific sets of Task Templates to add to our Gantt chart every ongoing Sprint / Version or any repeatable time period.